The primary goal of the Statistical and Data Coordinating Center (SDCC) of the American College of Surgeons Oncology Group (ACOSOG) is to assure that valid and defensible studies are designed, executed, and reported. The SDCC intends to accomplish this goal by implementing clinical trials management systems based on sound statistical principles, modern computing technology, and highly skilled personnel. Since the start of funding in May of 1998, the SDCC, and the ACOSOG as a whole, have concentrated on activating the initial set of studies. At this time (May, 1999) four studies are open and there have been 22 patient registrations. In order to have registered patients, the SDCC has built a considerable infrastructure, including a methodology for the production of protocols, a document distribution system (web site), databases, patient registration procedures, Standard Operating Procedure documents, and a patient data acquisition system. Additional supporting infrastructure was built to support two group meetings, a committee structure database, and a membership database. The assembled staff is highly qualified and has extensive experience in clinical trials. The ACOSOG has over 25 studies in various stages of development, and some of these are anticipated to open in the next few months. This proposal describes how the SDCC intends to provide the infrastructure for ACOSOG growth, continue recruitment of excellent staff, organize for maximum effectiveness, implement policies consistent with the primary goal, refine the systems already in place, and undertake new initiatives based on the use of modern technologies and concepts.